Serpula himantioides is a globally distributed saprotrophic fungus that is observed on all continents except Antarctica (Carlsen et al., 2011).Serpula himantioides mainly occurs on hardwood and softwood trees in natural environments, but it can also inhabit wooden structures (Carlsen et al., 2011). Brown rot caused by S. himantioides in the roots and stem base has been reported on various hosts (e.g. Pseudotsuga menziesii, Larix kaempferi) (Seehann, 1986). In Japan, the butt rot caused by S. himantioides has been reported in old stands of Chamaecyparis pisifera (Haraguchi et al., 2017, Figure 1a-c) and Abies sachalinensis. Molecular analyses have revealed that S. himantioides includes several cryptic lineages. Kauserud et al. (2004) conducted a phylogenetic analysis based on the internal transcribed spacer (ITS) region and the beta-tubulin (tub) gene and identified two lineages. In a follow-up study, Kauserud et al. (2006) performed a phylogenetic analysis based on four DNA regions [ITS, LSU, tub, and the heat stress protein gene (hsp)] with amplified fragment length polymorphisms (AFLPs) and defined three lineages. This study also showed that these three lineages are mutually incompatible, suggesting that they could be defined as biological species. Carlsen et al. (2011) similarly conducted phylogenetic analyses based on the same four DNA regions with additional samples from different regions around the world, Japan excluded, and concluded that S. himantioides consists of five cryptic lineages (PS1-PS5). In the study of Kauserud et al. (2004), a Japanese isolate used in the phylogenetic analysis based on the ITS region clustered with an
Evaluation of GerminationPromoting Treatments for Toxicodendron vernicifluum Seeds Based on Breaking Physical and Physiological Seed Dormancy. J Jpn For Soc 104: 254-261 The seeds of Toxicodendron vernicifluum are considered to be in a state of combinational dormancy, which is a combination of physical and physiological dormancy. To improve the germination rate of T. vernicifluum seeds, the methods reported to be effective in promoting seed germination were evaluated separately for breaking physical and physiological seed dormancy. The most effective methods for breaking physical dormancy of T. vernicifluum seeds were soaking in concentrated sulfuric acid (H 2 SO 4 ) for 60 to 120 min or partial removal of the endocarp. Water absorption was observed to begin at two locations on the seed after soaking in H 2 SO 4 for 90 min. Cold stratification for 4 to 12 weeks was effective in breaking physiological dormancy of the seeds after soaking in H 2 SO 4 . However, seeds treated with cold stratification after partial removal of endocarp did not germinate. The germination rate of seeds soaked in H 2 SO 4 for 90 min followed by 8 weeks of cold stratification (73.2±2.7%)was significantly higher than that of seeds soaked in H 2 SO 4 or cold stratification alone (0.8±1.0% and 0.4±0.9%, respectively) or no treatment (0.0±0.0), indicating that the combined treatment would be effective for improving T. vernicifluum germination.
To explore diversity in cold hardiness mechanisms, high resolution magnetic resonance imaging (MRI) was used to visualize freezing behaviors in wintering flower buds of Daphne kamtschatica var. jezoensis, which have no bud scales surrounding well-developed florets. MRI images showed that anthers remained stably supercooled to -14 ∼ -21°C or lower whilst most other tissues froze by -7°C. Freezing of some anthers detected in MRI images at ∼ -21°C corresponded with numerous low temperature exotherms and also with the “all-or-nothing” type of anther injuries. In ovules/pistils, only embryo sacs remained supercooled at -7°C or lower, but slowly dehydrated during further cooling. Cryomicroscopic observation revealed ice formation in the cavities of calyx tubes and pistils but detected no ice in embryo sacs or in anthers. The distribution of ice nucleation activity in floral tissues corroborated the tissue freezing behaviors. Filaments likely work as the ice blocking barrier that prevents ice intrusion from extracellularly frozen calyx tubes to connecting unfrozen anthers. Unique freezing behaviors were demonstrated in Daphne flower buds: preferential freezing avoidance in male and female gametophytes and their surrounding tissues (by stable supercooling in anthers and by supercooling with slow dehydration in embryo sacs) whilst the remaining tissues tolerate extracellular freezing.
affected not only by abiotic environmental factors such as desiccation stress (Suzuki and Kiyohara 1978), but also by biotic factors such as ectomycorrhizal association (Kikuchi et al. 1991).Ectomycorrhizae are a symbiotic association in which the host tree is associated with fungi. The host tree provides carbohydrates to the fungi via ectomycorrhizae, and, inversely, the fungi enhance host tree absorption of soil minerals and water (Finlay and Read 1986), improve host resistance to root disease (Marx 1969;Buscot et al. 1992), and ameliorate soil desiccation stress (Mexal and Reid 1973).Regarding the relationship between ectomycorrhizal abundance and pine wilt damage, Akema and Futai (2005) found that pine wilt damage was lighter and the rate of ectomycorrhizal root tips was higher on upper slopes than lower slopes. Thus, ectomycorrhizal abundance is thought to be related to pine wilt damage, but the causal association is not clear. Kikuchi et al. (1991) reported that mortality caused by inoculation by the pathogenic nematode was lower in P. densifl ora seedlings with ectomycorrhizae than without ectomycorrhizae. After inoculation of pathogenic nematodes on P. thunbergii seedlings, ectomycorrhizae did not disappear; however, ectomycorrhizal development ceased (Ichihara et al. 2001). To clarify this relationship, more fi eld observations and experiments are needed.Previous studies have not considered two potentially important factors: soil conditions and the ectomycorrhizal community structure. Akema and Futai (2005) reported a difference in soil moisture between the upper and lower slopes. Soil conditions such as soil moisture can infl uence ectomycorrhizal association (Slankis 1974). Thus, the effects of soil conditions should be considered to understand the relationship between ectomycorrhizal association and pine wilt damage. Neither Akema and Futai (2005) nor Ichihara et al. ( 2001) reported the ectomycorrhizal community structure on pine roots. Kikuchi et al. (1991) compared the different effects of ectomycorrhizal species on pine resistance, but they observed only two fungal species. The symbiotic function of ectomycorrhizae differs among fungal species (Nara 2006). Thus, not only the amount of ectomycorrhizae,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.